Prior art optoelectronic sensors devices for detecting precipitation on a transparent pane of a motor vehicle include a beam guide element. The beam guide element has a beam transmitter and a beam receiver. The beam transmitter transmits a beam to the pane. The beam transmitter includes a parallelizing component to cause the beam to propagate as an in-phase beam wavefront. A part of the beam transmitted to the pane passes through the pane into the outside environment. Another part of the beam transmitted to the pane is reflected by the pane. The reflection proportion is dependent upon the amount of precipitation on the pane. The reflected beam is then received by a beam receiver. The beam receiver includes a focusing component for focusing the reflected beam from the pane to the beam receiver. A problem with the prior art optoelectronic sensors is that the parallelizing and focusing components require a considerable length of installation space in addition to the space required by the beam guide element.